10.2. The Public Key Infrastructure (PKI)

10.2.1. Cryptographic Algorithms (Ciphers) Type

Cryptographic algorithms can be grouped into one-way and two-way algorithms, also known as ciphers: while two-way methods are intended to allow recovery of the original content, one-way methods are not intended to allow recovery. The two-way methods could be further organized into the three categories of symmetric, asymmetric, and hybrid. Typically, due to key management issues, asymmetric methods are more secure than symmetric methods; the trade-off is, however, that asymmetric methods are typically much more computationally intensive.

10.2.1.1. Two-way Symmetric Methods

These methods use the same key for encryption and decryption. This means that all people and software agents with access to a key can perform both encryption and decryption. Therefore, these methods are often referred to as the private key methods, because if the key was made public, then it would not be possible to control the membership of the group that allows access to information encrypted with symmetric methods.